Crystal Structures of the Extracellular Domain from PepT1 and PepT2 Provide Novel Insights into Mammalian Peptide Transport.
Crystal Structures of the Extracellular Domain from PepT1 and PepT2 Provide Novel Insights into Mammalian Peptide Transport.
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DOI：
10.1016/j.str.2015.07.016
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发表时间：
2015-10-06
期刊：
影响因子：
--
通讯作者：
Newstead S
中科院分区：
文献类型：
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作者：
Beale JH;Parker JL;Samsudin F;Barrett AL;Senan A;Bird LE;Scott D;Owens RJ;Sansom MSP;Tucker SJ;Meredith D;Fowler PW;Newstead S
哺乳动物通过PepT1和PepT2（质子偶联寡肽转运蛋白POT家族成员）的作用，在胃肠道中摄取二肽和三肽，从而获得氮。PepT1和PepT2在人体内的药物转运中也起着重要作用。最近的细菌同系物的晶体结构揭示了一个保守的肽结合位点和运输机制。然而，细菌和哺乳动物同源物之间存在一个关键的结构差异，只有后者含有一个大的细胞外结构域，其功能目前尚不清楚。在这里，我们提出了从PepT1和PepT2的细胞外结构域的晶体结构，揭示了两个免疫球蛋白样折叠串联连接，提供结构洞察哺乳动物肽转运。功能和生物物理研究表明，这些结构域与肠蛋白酶胰蛋白酶相互作用，表明在真核细胞中的肽转运位点的聚类蛋白水解活性的作用。PepT1和PepT2胞外结构域的晶体结构哺乳动物MFS转运蛋白的模块化结构胞外结构域含有免疫球蛋白样折叠并与胰蛋白酶相互作用PepT1和PepT2的晶体结构由Beale et al.揭示了两个串联连接的免疫球蛋白样结构域插入在典型的主要易化超家族折叠内。生物物理分析揭示了一个特定的相互作用与胰蛋白酶，这表明在集群蛋白水解活性的肽吸收跨膜的网站的作用。
Mammals obtain nitrogen via the uptake of di- and tri-peptides in the gastrointestinal tract through the action of PepT1 and PepT2, which are members of the POT family of proton-coupled oligopeptide transporters. PepT1 and PepT2 also play an important role in drug transport in the human body. Recent crystal structures of bacterial homologs revealed a conserved peptide-binding site and mechanism of transport. However, a key structural difference exists between bacterial and mammalian homologs with only the latter containing a large extracellular domain, the function of which is currently unknown. Here, we present the crystal structure of the extracellular domain from both PepT1 and PepT2 that reveal two immunoglobulin-like folds connected in tandem, providing structural insight into mammalian peptide transport. Functional and biophysical studies demonstrate that these domains interact with the intestinal protease trypsin, suggesting a role in clustering proteolytic activity to the site of peptide transport in eukaryotic cells. Crystal structure of the extracellular domains of PepT1 and PepT2 Modular architecture for a mammalian MFS transporter Extracellular domains contain immunoglobulin-like fold and interact with trypsin The crystal structure of PepT1 and PepT2 reported by Beale et al. reveals two immunoglobulin-like domains connected in tandem inserted within the canonical major facilitator superfamily fold. Biophysical analyses reveal a specific interaction with trypsin, suggesting a role in clustering proteolytic activity to the site of peptide uptake across the membrane.